Early stage: Acute attacks are often accompanied by symptoms of high or low fever, with sudden onset of swelling of the lumbar, hip and other joints, severe pain, bed rest, inability to turn over, resulting in large joints with bony ankylosis and deformity. Chronic insidious onset is often characterized by inconspicuous features, easily overlooked, and a high rate of early misdiagnosis. Therefore, awareness of the early symptoms of the disease is quite important, and early diagnosis and early treatment is a guarantee of clinical cure and reduced disability in ankylosing spondylitis. The early symptoms are pain in the sacroiliac region, low back, hip or large joints, accompanied by stiffness in the low back, which is most pronounced in the morning and can be reduced after activity. Expert advice: If you have constant or intermittent pain in the lumbosacral and hip areas, along with stiffness in the lower back, limited bending and squatting, or unexplained pain in the knee, heel, sternoclavicular, rib cage, metatarsal phalangeal and other small joints, you should be alerted to the possibility of ankylosing spondylitis, which can be diagnosed by an experienced specialist through pulse and physical signs combined with X-ray and HLA-B27. The diagnosis can be confirmed by combination of X-ray and HLA-B27 screening. In 90% of patients, the disease starts in the sacroiliac joints and progresses up the lumbar, thoracic, and cervical spine. The disease reaches the lumbar spine and manifests as lumbar spine back pain, lumbar forward flexion, back stiffness, limited bilateral movement, loss of normal physiological curvature of the lumbar spine or flattening, and in severe cases, lumbar muscle atrophy. The disease to the thoracic spine manifests as back pain, anterior chest and bilateral hypochondriac pain, restricted chest expansion, breathing pain, breath-holding, and easily causing hunchback deformity. The disease to the cervical spine manifests as pain in the cervical spine, upper limbs and head, neck straightening, restricted up and down, left and right rotation, inability to turn back, inability to look straight ahead, and turtle neck-like deformity. The disease gradually progresses to the advanced stage, when all joints of the spine have been straightened and fixed, pain has been significantly reduced, X-ray indicates that the spine shows bamboo-like changes, difficulty in movement and stiffness of joints, which makes patients suffer.